Dual-fuel engines are well known in the art and combust a mixture of two different types of fuel. For example, a particular dual-fuel engine can combust a mixture of a liquid fuel (e.g., diesel fuel) and a gaseous fuel (e.g., natural gas). By combusting two different types of fuel, advantages of both fuels (e.g., efficiency, power, emissions, cost, etc.) can be realized.
In order to properly control performance of a dual-fuel engine, the flow of each individual fuel should be known and tightly controlled. In many applications, the engine is started with the liquid fuel and, then after a period of time, the engine transitions to operation on the gaseous fuel. If the flow of the liquid and/or gaseous fuel is unknown and/or uncontrolled, caused for example by a fuel leak, the engine may be at risk of over or under-fueling. Either situation can result in a loss of performance and/or engine damage.
Historically, fuel leakage has been detected in several different ways. For example, U.S. Pat. No. 6,044,806 that issued to Brown et al. on Apr. 4, 2000 (“the '806 patent”) describes a dual-fuel engine having a leak detection system configured to check for a leaking gas admission valve in two different ways. The leak detection system includes a detonation sensor mounted to an engine block, and an electronic fuel governor. During a dual-fuel mode of operation, signals from the detonation sensor are compared to expected values. And when a significant deviation between the signals occurs, it is concluded that the gas admission valve is leaking. Similarly, a demand for liquid fuel by the governor is monitored before and after opening of the gas admission valve, and a difference in the demand is compared to an expected difference. When a significant increase in fuel demand occurs, it is again concluded that the gas admission valve is leaking. These methods can be used alone or together, as desired, to selectively control (e.g., shut off) gaseous fuel flow through the admission valve into the engine.
Although the system of the '806 patent may successfully detect gas leakage through an admission valve in a dual-fuel engine, it may still be limited. Specifically, the system may be able to detect only an internal gas leak and/or a gas leak caused by only the admission valve. Further, the location of the detonation sensor may not optimally detect detonation within every cylinder in a multi-cylinder engine.
The disclosed control system is directed to overcoming one or more of the problems set forth above.